README.md

@@ -146,8 +146,8 @@ Some of yt-dlp's default options are different from that of youtube-dl and youtu
 * Thumbnail embedding in `mp4` is done with mutagen if possible. Use `--compat-options embed-thumbnail-atomicparsley` to force the use of AtomicParsley instead
 * Some private fields such as filenames are removed by default from the infojson. Use `--no-clean-infojson` or `--compat-options no-clean-infojson` to revert this
 * When `--embed-subs` and `--write-subs` are used together, the subtitles are written to disk and also embedded in the media file. You can use just `--embed-subs` to embed the subs and automatically delete the separate file. See [#630 (comment)](https://github.com/yt-dlp/yt-dlp/issues/630#issuecomment-893659460) for more info. `--compat-options no-keep-subs` can be used to revert this
-* `certifi` will be used for SSL root certificates, if installed. If you want to use system certificates (e.g. self-signed), use `--compat-options no-certifi`
-* youtube-dl tries to remove some superfluous punctuations from filenames. While this can sometimes be helpfull, it is often undesirable. So yt-dlp tries to keep the fields in the filenames as close to their original values as possible. You can use `--compat-options filename-sanitization` to revert to youtube-dl's behavior
+* `certifi` will be used for SSL root certificates, if installed. If you want to use only system certificates, use `--compat-options no-certifi`
+* youtube-dl tries to remove some superfluous punctuations from filenames. While this can sometimes be helpful, it is often undesirable. So yt-dlp tries to keep the fields in the filenames as close to their original values as possible. You can use `--compat-options filename-sanitization` to revert to youtube-dl's behavior
 
 For ease of use, a few more compat options are available:
 

yt_dlp/YoutubeDL.py

@@ -2377,18 +2377,13 @@ class YoutubeDL:
             self.report_warning('"duration" field is negative, there is an error in extractor')
 
         chapters = info_dict.get('chapters') or []
-        if chapters and chapters[0].get('start_time'):
-            chapters.insert(0, {'start_time': 0})
-
         dummy_chapter = {'end_time': 0, 'start_time': info_dict.get('duration')}
-        for idx, (prev, current, next_) in enumerate(zip(
-                (dummy_chapter, *chapters), chapters, (*chapters[1:], dummy_chapter)), 1):
+        for prev, current, next_ in zip(
+                (dummy_chapter, *chapters), chapters, (*chapters[1:], dummy_chapter)):
             if current.get('start_time') is None:
                 current['start_time'] = prev.get('end_time')
             if not current.get('end_time'):
                 current['end_time'] = next_.get('start_time')
-            if not current.get('title'):
-                current['title'] = f'<Untitled Chapter {idx}>'
 
         if 'playlist' not in info_dict:
             # It isn't part of a playlist

yt_dlp/extractor/generic.py

@@ -111,6 +111,7 @@ from ..compat import compat_etree_fromstring
 from ..utils import (
     KNOWN_EXTENSIONS,
     ExtractorError,
+    HEADRequest,
     UnsupportedError,
     determine_ext,
     dict_get,
@@ -123,6 +124,7 @@ from ..utils import (
     orderedSet,
     parse_duration,
     parse_resolution,
+    sanitized_Request,
     smuggle_url,
     str_or_none,
     try_call,
@@ -2805,6 +2807,26 @@ class GenericIE(InfoExtractor):
         else:
             video_id = self._generic_id(url)
 
+        self.to_screen('%s: Requesting header' % video_id)
+
+        head_req = HEADRequest(url)
+        head_response = self._request_webpage(
+            head_req, video_id,
+            note=False, errnote='Could not send HEAD request to %s' % url,
+            fatal=False)
+
+        if head_response is not False:
+            # Check for redirect
+            new_url = head_response.geturl()
+            if url != new_url:
+                self.report_following_redirect(new_url)
+                if force_videoid:
+                    new_url = smuggle_url(
+                        new_url, {'force_videoid': force_videoid})
+                return self.url_result(new_url)
+
+        def request_webpage():
+            request = sanitized_Request(url)
             # Some webservers may serve compressed content of rather big size (e.g. gzipped flac)
             # making it impossible to download only chunk of the file (yet we need only 512kB to
             # test whether it's HTML or not). According to yt-dlp default Accept-Encoding
@@ -2812,23 +2834,22 @@ class GenericIE(InfoExtractor):
             # Therefore for extraction pass we have to override Accept-Encoding to any in order
             # to accept raw bytes and being able to download only a chunk.
             # It may probably better to solve this by checking Content-Type for application/octet-stream
-        # after a HEAD request, but not sure if we can rely on this.
-        full_response = self._request_webpage(url, video_id, headers={'Accept-Encoding': '*'})
-        new_url = full_response.geturl()
-        if url != new_url:
-            self.report_following_redirect(new_url)
-            if force_videoid:
-                new_url = smuggle_url(new_url, {'force_videoid': force_videoid})
-            return self.url_result(new_url)
+            # after HEAD request finishes, but not sure if we can rely on this.
+            request.add_header('Accept-Encoding', '*')
+            return self._request_webpage(request, video_id)
+
+        full_response = None
+        if head_response is False:
+            head_response = full_response = request_webpage()
 
         info_dict = {
             'id': video_id,
             'title': self._generic_title(url),
-            'timestamp': unified_timestamp(full_response.headers.get('Last-Modified'))
+            'timestamp': unified_timestamp(head_response.headers.get('Last-Modified'))
         }
 
         # Check for direct link to a video
-        content_type = full_response.headers.get('Content-Type', '').lower()
+        content_type = head_response.headers.get('Content-Type', '').lower()
         m = re.match(r'^(?P<type>audio|video|application(?=/(?:ogg$|(?:vnd\.apple\.|x-)?mpegurl)))/(?P<format_id>[^;\s]+)', content_type)
         if m:
             self.report_detected('direct video link')
@@ -2857,6 +2878,7 @@ class GenericIE(InfoExtractor):
             self.report_warning(
                 '%s on generic information extractor.' % ('Forcing' if force else 'Falling back'))
 
+        full_response = full_response or request_webpage()
         first_bytes = full_response.read(512)
 
         # Is it an M3U playlist?
@@ -4081,7 +4103,7 @@ class GenericIE(InfoExtractor):
                 webpage)
             if not found:
                 # Look also in Refresh HTTP header
-                refresh_header = full_response.headers.get('Refresh')
+                refresh_header = head_response.headers.get('Refresh')
                 if refresh_header:
                     found = re.search(REDIRECT_REGEX, refresh_header)
             if found:

yt_dlp/extractor/youtube.py

@@ -2764,15 +2764,17 @@ class YoutubeIE(YoutubeBaseInfoExtractor):
         if not strict:
             chapter_list.sort(key=lambda c: c['start_time'] or 0)
 
-        chapters = [{'start_time': 0}]
+        chapters = [{'start_time': 0, 'title': '<Untitled>'}]
         for idx, chapter in enumerate(chapter_list):
-            if chapter['start_time'] is None:
+            if chapter['start_time'] is None or not chapter['title']:
                 self.report_warning(f'Incomplete chapter {idx}')
             elif chapters[-1]['start_time'] <= chapter['start_time'] <= duration:
+                chapters[-1]['end_time'] = chapter['start_time']
                 chapters.append(chapter)
             else:
                 self.report_warning(f'Invalid start time for chapter "{chapter["title"]}"')
-        return chapters[1:]
+        chapters[-1]['end_time'] = duration
+        return chapters if len(chapters) > 1 and chapters[1]['start_time'] else chapters[1:]
 
     def _extract_comment(self, comment_renderer, parent=None):
         comment_id = comment_renderer.get('commentId')

yt_dlp/utils.py

@@ -950,7 +950,6 @@ def make_HTTPS_handler(params, **kwargs):
     if opts_check_certificate:
         if has_certifi and 'no-certifi' not in params.get('compat_opts', []):
             context.load_verify_locations(cafile=certifi.where())
-        else:
         try:
             context.load_default_certs()
         # Work around the issue in load_default_certs when there are bad certificates. See: